Engineering dual-functional VB2 nanoparticles in MgH2 for highly efficient hydrogen storage

Introduction of reactive additives into MgH 2 is a promising strategy for improving the hydrogen storage performances, but the inevitable formation of inert by-products degrades the effective capacity. In this work, a dual-functional additive, amorphous VB 2 nanoparticles , is introduced into MgH 2 by ball milling , which significantly lowers the working temperatures by over 120 °C without a huge capacity loss. VB 2 reacts with MgH 2 to in-situ form V and MgB 2 during ball milling and dehydrogenation , in which V remains unchanged during cycling and MgB 2 is hydrogen-storage-active that can absorb hydrogen. In addition, V acts as an active catalyst, which provides nucleation sites and decreases the apparent activation energy . Therefore, both the products from this VB 2 additive can make contributions to the hydrogen storage performances, showing a dual-functional effect.